Field of the Invention
The present invention relates to a method and system for handover of a user equipment in cell based networks, preferably in a femtocell network, comprising a user equipment, at least two base stations, wherein each base station is assigned to a cell, wherein coverage areas of at least two neighbouring cells are at least partly overlapping and wherein the user equipment is connected to one of the base stations, preferably in form of a femtocell base station, and wherein the at least two base stations are each connected via a backhaul connection to a core network device located in a core network.
Description of the Related Art
Although in general applicable to cell based networks, the present invention will be described with regard to femtocell networks.
The term “connection quality” preferably in the description, in particular in the claims is to be understood as any parameter indicating a predetermined level of quality of a connection. A connection may be in particular established by an application and may be based on IP-flows, bearers, or any other type of traffic aggregate.
In conventional telecommunication network deployments a so-called over-provisioning is used in backhaul connections to core networks in order to guarantee high levels of end-user quality of experience (QoE). With the advent of technologies, such as femtocells, cheap small-bandwidth lines are used to backhaul cellular communications which are shared amongst multiple users and services. Therefore, these backhaul connections may be a “bottleneck” due to their limited capacity when for example a user equipment is connected to a femtocell and further via small bandwidth link, e.g., a DSL link, to a server on the Internet.
When a user starts a quality of service (QoS) sensitive application on his user equipment which is connected to such a femtocell base station, the user may experience poor quality of his application when the quality of service requirements cannot be met by the backhaul connection. Similar a running application on the user equipment may experience a significant deterioration of connection quality, for example if other services increase their network usage.
In US 2011/0053599 A1 a method of a handover procedure is shown: A status of a backhaul connection between an original femtocell base station and a backhaul network is detected and then a handover request message including a reason code and/or flag to at least one mobile station served by the original femtocell base station is sent. The at least one mobile station then reassociates with at least one base station other than the original femtocell base station. A user equipment is therefore handed over to a neighbouring base station, in case the original femtocell base station experiences a backhaul failure or needs to reconfigure used frontend channels by the user equipment. The original femtocell base station sends then a flag to the user equipment and initiates a handover of the user equipment to another base station. The user equipment remains camped on the other base station until the original femtocell sends a callback command to the user equipment via the other base station. The user equipment would then be switched back to the original femtocell base station.
U.S. Pat. No. 7,200,401 B1 shows a communication network system and a method realizing an operator forced handover to another type of radio access network. For example, a speech service is provided for roaming users only via a GSM radio access network. When the connection is established via a UMTS RAN, in case the subscriber is a visiting one, the connection is handed over to the GSM radio access network. The capacity of the UMTS band can then be dedicated preferably to packet data services.
In US 2006/0194582 A1 a method of facilitating a handover from an active network with which a user equipment is in communication to another network is shown: A list of available other networks to said user equipment via the active network is provided. In the user equipment among the available networks based on preference information and signalling to said active network at least one preferred other network is selected. Via the active network neighbour cell information for the at least one preferred other network to said user equipment is provided.
One of the disadvantages of conventional methods and systems is that a modification of the 3GPP standard is required. Another disadvantage is that these conventional methods and systems are limited to macrocell networks.